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A Story of Us
A Story of Us
A New Look at Human Evolution
Lesley Newson and Peter J. Richerson
1
3
Oxford University Press is a department of the University of Oxford. It furthers
the University’s objective of excellence in research, scholarship, and education
by publishing worldwide. Oxford is a registered trade mark of Oxford University
Press in the UK and certain other countries.
Published in the United States of America by Oxford University Press
198 Madison Avenue, New York, NY 10016, United States of America.
© Lesley Newson and Peter J. Richerson 2021
All rights reserved. No part of this publication may be reproduced, stored in
a retrieval system, or transmitted, in any form or by any means, without the
prior permission in writing of Oxford University Press, or as expressly permitted
by law, by license, or under terms agreed with the appropriate reproduction
rights organization. Inquiries concerning reproduction outside the scope of the
above should be sent to the Rights Department, Oxford University Press, at the
address above.
You must not circulate this work in any other form
and you must impose this same condition on any acquirer.
Library of Congress Cataloging-in-Publication Data
Names: Newson, Lesley, author. | Richerson, Peter J., author.
Title: A story of us : a new look at human evolution /
by Lesley Newson & Peter J. Richerson.
Description: New York, NY : Oxford University Press, [2021] |
Includes bibliographical references and index.
Identifiers: LCCN 2020032769 (print) | LCCN 2020032770 (ebook) |
ISBN 9780190883201 (hardback) | ISBN 9780190883225 (epub)
Subjects: LCSH: Human evolution.
Classification: LCC GN281.4 N49 2021 (print) |
LCC GN281.4 (ebook) |DDC 599.93/8‒dc23
LC record available at https://lccn.loc.gov/2020032769
LC ebook record available at https://lccn.loc.gov/2020032770
DOI: 10.1093/ oso/ 9780190883201.001.0001
1 3 5 7 9 8 6 4 2
Printed by Sheridan Books, Inc., United States of America
To our descendants: Scott, Kate, Emily, Sophie, Alex, Peter, Jonah,
and those who haven’t been born yet.
Contents
Acknowledgments ix
1. Getting Beyond the Apemen 1
2. Ape Ancestor (About Seven Million Years Ago) 19
3. Apes That Walked Upright (About Three Million Years Ago) 38
4. Early Humans (About 1.5 Million Years Ago) 59
5. Humans Like Us (About 100,000 Years Ago) 79
6. Ice Age Humans (30,000 Years Ago) 113
7. Building Today’s World 144
8. Another Transformation: Modern Times 188
Epilogue 231
Notes 237
Bibliography 277
Index 303
Acknowledgments
The ideas and information we drew upon to write this book have been thought
of, discovered, and shaped by thousands of people. A good portion of those
people are mentioned in the notes so that readers can find out more about
their work.
But we owe a special debt to the many friends and colleagues who helped
shape our ideas of human evolution. First and foremost is Pete’s long-time
co-conspirator and friend Rob Boyd. The others we want to especially thank
are Billy Baum, Bob Bettinger, Don Campbell, Tim Caro, Dwight Collins, Bill
Davis, Jerry Edelman, Russ Genet, Alex Haslam, Joe Henrich, Katie Hinde,
Sarah Hrdy, Kevin Laland, Stephen Lea, Bill Mason, Richard McElreath,
Monique Borgerhoff Mulder, Robert Murphey, Tom Postmes, Joan Silk, John
Odling-Smee, Mark Thomas, Colin Tudge, Paul Webley, Bruce Winterhalder,
and Andy Whiten. And then there are the graduate students who taught us
so much. These include Bret Beheim, Adrian Bell, Lien-Siang Chou, Viken
Hillis, Nicole Naar, Brian Paciotti, Lore Ruttan, Bryan Vila, Tim Waring,
and Matt Zefferman. And thank you to the Department of Environmental
Science and Policy at University of California, Davis, which has been such a
congenial home.
There were also people who provided ideas and advice on the actual writing
of the book, listening to us, giving us feedback and reading chapters (including
some appalling early drafts): Marion Blute, Barry Bogin, Joseph Carroll,
Marilu Carter, Howard Cornell, Andreas De Block, Michael Fitzgerald, James
Gaasch, Mark Grote, Susan Harrison, Sue Hodgson, Beth Jaffe, Graham Jelfs,
Don Lotter, Mary Brooke McElreath, Cristina Moya, Peter Pascoe, Susan
Pitcher, Dorothy Place, Sarit Richerson, Peter Thompson, Roman Wittig,
Sydney Wood, Vedder Wright, and Devon Zagory.
Five people put a great deal of work into helping us, reading each of the
chapters, suggesting improvements and keeping us company. They are Jeff
Alexander, Sarah Brearly, Kristin Rauch, Nancy Redpath, and Debbie Worland.
We are very grateful to our illustrator, Jan Nerding, who also made many
useful comments on the manuscript, and to Maurice Simmons who imagined
two of our early ancestors.
And finally, thanks so much to Luba Ostashevsky, our agent, friend, muse,
and the midwife of this book.
1
Getting Beyond the Apemen
What is it to be human? With your first breath, you began your lifelong ex-
ploration of this question. You slowly tried to work out how to be comfortable
in your body and the world around you. You needed others to care for you,
and you automatically behaved in ways that encouraged them to care. Your
eyes were attracted to their faces and you stared back into their eyes. Your lips
stretched themselves into little smiles. You cried when you felt uncomfortable.
Your life has been intertwined with the lives of other people from the moment
you were conceived.
Scientists want to understand how our species evolved because they believe
it will shed light on the question of what it is to be human. Speculation about
human evolution has been going on for over 150 years, but it wasn’t until the
middle of the 20th century that stories of human evolution began to be told to
the general public. The scientists telling these stories had very little evidence
to go on—just a few fragments of human-like bones and teeth that archaeolo-
gists had found. But they thought they understood enough about people to
put together a good story. They confidently described apemen fighting over
women and territory on the African savanna. It was a story that made sense
to people who had recently experienced a devastating war and felt a little un-
comfortable talking about sex in “polite company.”1 Talking about our animal
ancestors’ sex lives was acceptable but still a little titillating.
The world has moved on since these days, but the apemen stories didn’t
change much. By the 1990s, scientists were less interested in how the apemen
fought and more interested in how they thought. The stories told by these
“evolutionary psychologists” were still about apemen in the savanna, but these
apemen were processing information and calculating how to defend territory
and get the most females.
In recent years, scientists have released a torrent of new information about
what our ancestors were like and how they lived their lives.2 It’s now possible
to tell a bigger, bolder, and richer story of human evolution, and our purpose
in writing this book is to tell such a story. When we were in the final stages of
writing it, world events provided a new demonstration of why a new story is
2 A story of us
needed. In a matter of days, people found their lives dramatically changed

as population after population attempted to slow the spread of a new virus.
Many people were compelled to stay at home to reduce their risk of catching
the virus, while others were asked to risk infection and go to work, caring for
the sick and supporting those sheltering at home. Scientists with relevant ex-
pertise worked at trying to better understand the virus and its spread, and to
find ways of treating and/or preventing infections. There was talk of “national
emergencies” and being “at war,” but this was a different kind of war. It wasn’t
a war of one group of humans against another group. Instead, all humans were
urged to unite to confront a common enemy—the virus.
Efforts to fight this invisible enemy were often shambolic, and any “unity”
achieved was far from perfect. But the global response to this virus in 2020
was very different from what would have happened if a virus like this had
emerged in the middle of the 20th century. Most 21st-century people ex-
pected (and hoped) that humans would work together, not only to defeat
the virus, but also to protect the complex social and economic bonds of our
shared world.
Our story of human evolution explains how the descendants of apes living
in an African forest could have evolved into the kind of animal that behaves
like this (see Figure 1.1). It’s not a complete story—far from it. And, without
doubt, future investigations will turn up evidence that reveals new details.
These may support or challenge parts of this story. That’s how science works.
But our story is certainly “truer” and more complete than the old apemen
stories.3 Also, it’s long past time to tell a story that weaves in the new evidence
and talks about all the interesting things that women and children were doing
as human beings evolved.4
New ways of thinking about thinking
When humans puzzle over something abstract like “what is thinking?,” we

can’t help but draw on our experiences with the concrete everyday world.
Once scientists started using computers, they began to conceive of “thinking”
as being like computing. They started to see a brain as a data processing and
storage device like a computer. Since then, ideas about brain evolution have
closely tracked the development of computers. In the 1990s scientists shared
their offices with a desktop computer that had a floppy disk drive and a chunky
monitor. They were excited about the performance of their new PC clone with
a Pentium chip and a Windows 95 operating system. So when scientists in the
1990s thought about how the brain evolved, they were inclined to think about
Getting beyond the apemen 3
Figure 1.1 The path from the forest.
hardware upgrades, imagining improvements in things like processing speed

and storage capacity. They saw genes as being like programs, and natural se-
lection as being like a software designer.
Computers have changed a lot in the past 25 years. Computer networks
were rudimentary in the 1990s. The explosive growth of the Internet and
the proliferation of connected devices changed everything. It also gave us a
much better metaphor for how the human brain works. Networked, mobile
4 A story of us
computers can do much more than the desktop computer of the 1990s. This
isn’t just because they’re better at storing and handling data. What’s really
important is their ability to share data, programs, and processing power.
The connectedness of today’s computers has helped scientists to realize that
the computer inside the human skull also owes much of its power to its
ability to be in a network—to be part of an “us.” We humans learn from
others. We put our heads together and think things over. We share our
feelings and feel each other’s pain. Connectedness is vital for our mental
health. Children who have been neglected and not allowed social contact
don’t just grow up ignorant of the world; their brain development is often
delayed or impaired.5
Our ability and our need to be connected evolved because being connected
made our ancestors successful. The stories of human evolution that we share
and tell our children need to change to reflect this new understanding. But
even more important, they need to reflect all the new evidence about our an-
cestors that doesn’t fit into the violent apemen on the savanna story. For ex-
ample, we now know much more about what our female ancestors were doing
and what children’s lives were like.6 This is in no small part due to the many
brilliant women scientists who have risen through the academic ranks to
positions that allow them to influence research topics.7 Knowing more about
children’s lives is vitally important for understanding human evolution, be-
cause it’s during childhood that the competition for survival is most acute.8
Even a hundred years ago it was common in some populations for half the
babies to die before reaching adulthood. We must never forget that, over the
millennia, our ancestors were the ones who not only made it to adulthood,
but also had children who made it to adulthood and went on to have children
themselves.
You might think that there is nothing complicated or special about humans
raising their young. Producing offspring is, after all, something all animals
do. But this view is deceptive. In evolutionary terms, producing offspring that
survive is the most important thing animals do. In most species of mammal,
the female does all the work of raising the young. In humans, mothers get help
and support from other women and from the men in their lives. Whether they
were hunters, farmers, soldiers, or something else, men’s work was important
for our evolution because it contributed to the survival of children. A key and
recurring theme in the story of human evolution is how men’s efforts have
been harnessed and applied to the raising of offspring.
Today’s evolutionary scientists are also less keen to try to learn about a
gene-defined “human nature.” In fact, the whole “human nature” idea is
looking more and more bogus.9 Awkward family gatherings may be difficult
to endure, but they provide ideal opportunities to observe that people who
are raised together and share a lot of the same genes don’t necessarily behave
in the same way. Neither genes nor environment do a good job of predicting
how our children will turn out. Neither factor (alone or in combination)
can explain why a challenge that makes one child resilient can scar another
child for life. There is other stuff going on to make us what we are, including
random factors. We may have to accept, like our ancestors did, that some
stuff just happens—call it luck or “fate.” Not all the influences in our lives
can be pinned down and explained. Humans haven’t evolved a mind pro-
grammed to respond in certain ways. We evolved a mind that could evolve,
and it has made us what we are today—a very different animal.
Stories are tools for thinking, and so

is evidence
Seven million years ago, our ancestors were apes that lived in forests in Africa.
These apes are also the ancestors of the chimpanzees and bonobos that still
live in Africa today. While their side of the family stayed put, our ancestors
left the forest and produced descendants that eventually became scattered all
over the world. The paths our ancestors took over the last seven million years
are being investigated by legions of scientists, and their work is revealing more
and more details.
Evidence is always better at showing what could not have happened than re-
vealing for certain what did happen. That’s why stories are valuable. By pulling
together threads of evidence from many disciplines, it’s possible to weave to-
gether ideas about the dramas that our ancestors might have starred in. We
can even make educated guesses about what it felt like to be them. It was
the challenges they faced, the solutions they found, and the trade-offs they
made that shaped what we have become. To understand our ancestors, it’s not
enough to simply imagine how we might have faced those challenges or how
we might have felt. We must think ourselves outside of the time and place we
live in now. Our ancestors didn’t just face different problems; they had life-
times of different experiences and were steeped in different knowledge and
beliefs. Our more ancient ancestors were physically different, and their minds
had different capacities. They weren’t capable of thinking and feeling like we
do. And even quite recent ancestors, who may have looked just like people
today, would have thought and felt differently.
Humans have long used stories to launch their imagination into situ-
ations they could never experience in their own lives. That’s why this book is
6 A story of us
illustrated with stories about events that could have taken place in our ances-
tors’ lives. All scientists are storytellers, constantly using their imagination to
try to make sense of the evidence they’re gathering. The stories others have
told are the inspiration for the ones that we have written for this book. The
foundations of our ancestors’ evolutionary success were laid during their
childhood, when their lives were most at risk, so our stories are mostly set in
this part of their lives. Our ancestors didn’t just survive the dangers; they were
able to make the most of the situations they found themselves in.
The stories we tell get longer as the evolutionary process brings increasing
complexity to our ancestors’ lives. And each one is followed by a summary
of the evidence and theories that we drew on to write the story. Readers ac-
customed to reading scientific literature will probably want to know more
about the evidence we relied on. They may also want to know the names
of the academics whose research and scholarship provided this evidence.
For the benefit of these readers, the chapters are peppered with numbers
that link to a note in a section at the back of the book. These notes give
more detail and/or suggest further reading. We have written the book in this
“multi-level” way because we believe that stories of our origins belong to all
humans, not just to those who are trained in science or fascinated by it. If
you’re just interested in the story and find the labors of academics boring,
don’t bother with the notes. Or try them out when you have insomnia, in
lieu of some other sleep aid!
Many people would rather not be told a story about humans being animals
and a product of the evolutionary processes described by Charles Darwin.
People’s reactions to Darwin’s ideas provide a good illustration of the diver-
sity of our species. Some of us see it as obviously true that humans evolved by
natural selection—“survival of the fittest”—and believe this view to be well
supported by evidence. Others reject the idea, see it as obviously false, and
quote plenty of evidence to show why it can’t be true. Both sides have a point.
The close connectedness of humans and our reliance on one another is con-
vincing evidence that human evolution wasn’t just a matter of survival of the
fittest. Darwin saw that too. Humans may be animals, but we aren’t just an-
other animal. The evolution of an animal like us is so unlikely that scholars
have puzzled and argued for a long time over how it could have happened. An
animal like us could have only evolved in certain very unusual circumstances.
This means that, if humans are a product of evolution, we can rule out a lot
of scenarios about our past that can’t possibly be true. In developing the story
of our evolution, we must imagine the kinds of things that might have hap-
pened to make the evolution of an animal like us possible. The story of our
evolution is amazing and unique. We humans have a history we can be proud

of—well, maybe not all of it.
The special species
Nowadays, many people believe there’s nothing special about humans—

that we are “just” another animal. This wasn’t the case in 1858 when Charles
Darwin presented his idea of evolution by natural selection. His book On the
Origin of Species, published the following year, was a bestseller (for a nonfic-
tion book), and readers were impressed by the large body of evidence he had
pulled together. Even so, a lot of them struggled with the basic idea. It seemed
to strip life of its meaning and purpose except for some all-consuming need to
compete, survive, and leave offspring. They didn’t feel that this was what their
lives were all about. This feeling (or need for a feeling) that our lives are about
something is one of the things that is special about humans. Darwin went on
to write The Descent of Man in 1871, another great book, but it left most of his
critics unsatisfied.10
Alfred Russel Wallace11 believed that understanding human specialness re-
quired looking beyond the physical world. Like Darwin, Wallace was a 19th-
century British naturalist and explorer with a beard. He spent much of the
early part of his life exploring in the tropics, observing the animals, plants, and
people who lived there. Like Darwin, he collected many specimens and sent
them back to England. It was in 1858, when he was 34 years old and exploring
the islands that are now part of Indonesia, that he worked out the theory of
evolution by natural selection.
Like most well-read English men and women of his time, Wallace was fa-
miliar with the evidence that the Earth and its life had changed (or “evolved”)
over time. There were fossilized remains of strange plants and animals that no
longer existed. More and more of these remains were being found all the time.
What’s more, remains of sea creatures were often found embedded in rock on
the tops of mountains, hundreds of miles from the coast. What force or forces
were driving these changes? Wallace enjoyed puzzling over such questions
with friends and colleagues. It was when he was recovering from malaria (and
perhaps a little feverish) that he realized that there didn’t need to be a super-
natural force driving the change in living organisms.
The struggle for survival could be that force. This struggle was something
Wallace witnessed all the time as he explored the tropical islands. When living
things reproduced, they created far more offspring than could possibly sur-
vive, so there was constant competition. Animals competed to find food, trees
8 A story of us
competed to get their leaves into the sunlight, and everything tried to avoid
being food for something else. Individual organisms were not all the same,
and some had characteristics that made them better suited to the environ-
ment. They were the ones most likely to survive long enough to reproduce.
If the offspring of these survivors inherit their parents’ characteristics, then
the population of organisms is bound to change with each generation. The
new generation will be slightly better suited to the environment than the
previous one.
As soon as he was well enough, Wallace wrote to Charles Darwin ex-
plaining his idea. He and Darwin had been exchanging letters for two years,
but Wallace didn’t know that Darwin had already had the same idea. Back in
England, Darwin had been quietly developing his theory about how compe-
tition to survive and leave offspring could be a natural mechanism for evo-
lution. He had talked about it with close friends but didn’t want to discuss it
more widely until he had built up a good body of evidence and examples to
show that it was more than just a notion. Once he realized that someone else
was thinking along the same lines, he arranged for Wallace’s letter, along with
a paper of his own, to be read at a meeting of the Linnean Society of London
in 1858. At that time, the Linnean Society was one of the primary organiza-
tions discussing new discoveries in natural history, and by having the idea
presented in this way, Darwin ensured that both he and Wallace would be
credited with thinking of it (see Figure 1.2).
Still in Indonesia, Wallace knew nothing of this, but he eventually received
letters telling him what a stir the idea was causing among naturalists. He
continued his exploration of the islands for another four years, returning to
England in 1862 to find that everyone interested in evolution was discussing
Darwin’s Origin of Species, which had been out for over two years. There’s no
evidence that Wallace had any grievance with Darwin about how he and his
idea had been treated. In fact, he began to give public lectures explaining his
and Darwin’s shared view of how natural selection could have “created” the
vast diversity of life.
It soon became clear, however, that Wallace’s view of human evolution dif-
fered from Darwin’s in an important way. Wallace believed that the evolution
of the physical characteristics of living things could have come about through
millions of generations of organisms competing to survive. But he couldn’t
see how the consciousness and the conscience of humans could have come
about in this way. In his travels, he had seen countless examples of animals
and plants competing. He had observed many times the suffering and death
of creatures with an injury or illness that had made them less able to survive.
A small wound or slight malaise was often fatal.
Figure 1.2 The two sides of the medal issued by the Linnean Society of London to
commemorate the 50th anniversary of the reading of Darwin and Wallace’s papers on
evolution by natural selection.
This was far less likely in the humans that Wallace had observed. During
his travels in South America and Indonesia, he had met many peoples whom
his friends back in Europe would call “savages.” The various tribes looked
and behaved very differently from Europeans, and also very differently from
each other. But he found that all the humans he met were the same in an im-
portant way. In an essay he wrote for the Journal of the Anthropological Society
of London, he described it like this:
In the rudest tribes the sick are assisted at least with food; less robust health and
vigor than the average does not entail death. Neither does the want of perfect limbs
or other organs produce the same effects as among animals. Some division of labor
takes place; the swiftest hunt, the less active fish, or gather fruits; food is to some
extent exchanged or divided. The action of natural selection is therefore checked;
the weaker, the dwarfish, those of less active limbs, or less piercing eyesight, do not
suffer the extreme penalty which falls upon animals so defective.12
10 A story of us
Wallace concluded that humans don’t compete like other animals, and that
this meant natural selection would not work in the same way as it did with
other living things. He also wondered what could account for the generosity
that seemed to be universal in humans and yet, he thought, completely ab-
sent in other animals. He speculated that human evolution might be different
and that some other evolutionary process might be necessary to explain the
development of the moral beliefs and mental life of humans. He wondered
if this evolution could be occurring outside of the immediately observable
physical world.
And why not? Up in Scotland, the physicist James Clerk Maxwell was dem-
onstrating that electric and magnetic fields travel through space as invisible
waves, moving at the speed of light. So much of what had been thought of
as “supernatural” was becoming understood to be part of nature. There was
a sense that many amazing new discoveries were just around the corner. In
the 1860s there was much discussion of the possibility that an invisible “spirit
world” might also be part of nature. Wallace, like a number of scientists at the
time, believed that if such a world did exist, the possibility of communicating
with spirits should be systematically investigated. He thought that, in spirit
form, the human mind might evolve separately from a physical body.
Wallace attended some séances and heard knocking alleged to be made by
disembodied spirits. He spoke to his dead relatives through mediums, and he
even had his photograph taken with an apparition of his dead mother. Some
of the people who produced such “supernatural phenomena” later admitted
that they were frauds. Even so, Wallace remained convinced that some of the
communications he’d had with the spirit world were genuine.
Nowadays, Darwin is given most of the credit for developing the theory of
evolution by natural selection because of the huge amount of work he did to
present evidence to support the theory. Today’s scientists admire Darwin for
his determination to be guided by that evidence rather than the fashionable
ideas of his time. Darwin didn’t think much of the spirit world idea, but he
completely agreed with Wallace that explaining human evolution presented
a problem. They both believed that all living things are related and that it’s
possible to compile a great family tree of life. Gaps in this family tree were
constantly being filled in during Darwin’s lifetime as his colleagues explored
the world finding more living specimens and fossils of organisms that had
died out. Many more gaps have been filled in since Darwin’s time. Our new
ability to sequence the DNA of living organisms and, in some cases, DNA re-
covered from the remains of long dead organisms is making a big contribu-
tion as well. Biologists are now able to more precisely position the many limbs
and branches of the tree of life.
Darwin saw that humans had a place on the tree, even if our species had to
be put way out on a limb. It must have irritated him that popular writers of
the time misquoted him as claiming that humans are descended from mon-
keys. Darwin put humans on the same branch of the tree as the great apes of
Africa (chimpanzees and gorillas) and believed us to be more distantly re-
lated to another kind of great ape, the orangutan, found on the Indonesian
islands of Borneo and Sumatra. Monkeys are more distant relatives. Their
faces may look human-like, but their bodies are very different. Most of them
have a tail, for example. Darwin lived long before anyone knew anything of
DNA or genes or how characteristics are passed from parents to offspring. His
judgments were based on painstaking observations—both his own and those
of his naturalist colleagues. DNA analyses have shown these judgments to be
mostly correct.
Darwin’s determination to base his judgments on evidence made his views
about human evolution, which he published in 1871,13 less popular than his
earlier book on the origin of species. At the time, his views were less influ-
ential than those of some other scholars. Herbert Spencer was the celebrity
pundit for human evolution. Spencer wasn’t just very eloquent; he also seemed
to be very sensitive to what the public wanted to hear.14 Darwin disagreed
with Spencer and many others who justified their countrymen’s treatment of
non-Europeans with the claim that other “races” are inferior or somehow less
human. Darwin argued that the physical differences between peoples are so
superficial that a biologist must conclude that not only do all humans belong
to the same species, but that we are all closely related. He agreed that people
raised in different environments behave differently, but he argued that experi-
ences influence behavior. In his 1871 book The Descent of Man, he presented
evidence that when young people from different parts of the world spend time
in Europe and are encouraged to adopt European ways, they behave just like
Europeans.
Darwin gained firsthand experience of this thanks to his five-year voyage
around the world on the British naval vessel called HMS Beagle. He spent
quite a bit of time with a young man whom the English called Jemmy Button.15
Darwin and Button were on the Beagle together when the 90-foot-long, 242-
ton bark set sail from England in 1829, crammed with 73 people and the pro-
visions and equipment they would need for the first part of their journey. The
main purpose of the journey was to survey South America to make more de-
tailed maps of its coast.
Darwin, aged 22, was going along to be the ship’s naturalist. His job was
to disembark and explore the land as the Beagle sailed along the coasts. He
planned to collect specimens of plants, animals, and rocks and send them back
12 A story of us
to England. Jemmy Button was on the Beagle to be taken back to his homeland.
On the ship’s previous voyage to South America two years earlier, the cap-
tain had picked up (kidnapped) four natives and decided to take them back
to England. Button was one of the three that survived. Living with English
people had transformed him. When the Beagle crew first encountered him,
he was a scrawny child swimming naked with his friends in the near-freezing
seawater that surrounded the ship. By the time Darwin met him, he was a ra-
ther plump teenager, dressed in the latest London fashion, with perfect table
manners and the Christian values of the English people he had lodged with.
The captain hoped that, once back with his people, he would be able to teach
them Christianity and the “civilized” ways he had learned in England.
After many adventures, including nearly sinking in a storm, the Beagle was
able to moor off Button’s homeland on Tierra del Fuego on the southern tip
of South America. Contact was made with his family and, after building him
a small house and planting some crops for him to harvest, the officers and
crew of the Beagle reluctantly left their well-dressed adoptee surrounded by
people whom they all, including Button, regarded as murderous and thieving
savages.
A year later, after completing a survey of the east coast of South America,
the Beagle sailed back to Button’s homeland to see how he was getting along.
The crew feared they would find him ill, half-starved, or worse. As soon as
Button heard that the Beagle had returned, he came out in a canoe to where
the ship was anchored. The lean young savage who climbed aboard had dirty
matted hair and, despite the cold, was naked apart from a small cloth tied
around his private parts (see Figures 1.3 and 1.4). Darwin wrote in a letter
home that “[i]‌t was quite painful to behold him . . . when he left us, he was
very fat and so particular about his clothes that he was always afraid of even
dirtying his shoes; scarcely ever without gloves and his hair neatly cut. I never
saw so complete and grievous a change.”
After Button boarded the Beagle, he immediately went below to wash and
borrow some clothes. He emerged much more like the man they had known
and was clearly thrilled to be with his English friends again. But when they
urged him to stay on board and sail back to England with them, he looked
surprised. He insisted that life with his people was good, telling the captain,
“I am hearty, sir, never better.” In his letter home, Darwin wrote that when
they’d left him with his fellow Fuegians in 1833, Button had been appalled at
the ignorance of his people and declared them “damn fools.” But he now saw
them, according to Darwin, as “very good people with too much to eat and all
the luxuries of life.” Button and some of his family members stayed on board
for the rest of the day, and the crew continued trying to persuade him to come
Figures 1.3 and 1.4 Sketches of Jemmy Button by Conrad Martens, the artist who was part of
the crew of HMS Beagle. The one on the left was made before they left Button among his people
on the island of Tierra del Fuego at the southern tip of South America. The one on the right is of
Button a year later when the ship returned and offered to take him back to England.
14 A story of us
with them back to England. Then a canoe arrived at the ship carrying a young
woman who was clearly upset. She was revealed to be Button’s wife, worried
that her husband would be spirited away. Darwin and the Beagle crew then
agreed that Button couldn’t possibly leave and gave him their enthusiastic
congratulations on his marriage.
Button stayed in South America but had several more contacts with
Europeans as they tried to claim and “tame” his land. He used his knowledge
of his own culture and that of the English to protect his people as best he
could, drawing on his understanding of the Europeans’ Christian values. He
died in his late forties when an epidemic struck his people. It was probably one
of the infectious diseases, like plague or measles, that Europeans brought to
the Americas.
The transformations in Button’s behavior had a big impact on Darwin.
He saw that no other animal, including apes, behaves as we do,16 and that
there are no examples of primitive humans that can serve as “missing links”
between humans and the animals that we are most closely related to. What’s
more, no other animal shows more than a fraction of the diversity of be-
havior that can be seen in a small village of humans. A biologist observing
human behavior might think to divide the human population into hundreds
of different species. But humans are closely related and very similar phys-
ically. Darwin’s time with Jemmy Button showed him how flexible the be-
havior of a single human can be, and that we don’t inherit our behavior from
our parents in the same way as we inherit the shape of our nose or the color
of our eyes.
There was what Darwin called a “great gap” on the ape branch of the family
tree between humans and chimpanzees, gorillas, and orangutans. In the years
since Darwin’s death, scientists have struggled to define the nature of that
“gap.” It’s taken for granted that humans are much more intelligent than other
animals, but what does that mean, exactly? The precise kind of intelligence
that humans possess may be unique, but other animals show great ingenuity
in solving the problems that are important in their own lives. Once scientists
developed tests of intellect that were better suited to the animals they were
studying, or when they simply started watching animals in the wild more
closely, they found them to be cleverer than they had imagined.17 Animals
with brains much smaller than ours are good learners with amazing mem-
ories. They’re also creative. Caledonian crows readily make tools out of twigs
and leaves to pull edible insect larvae out of holes. Humpback whales work
together to capture schools of tiny fish by blowing out a curtain of bubbles that
acts like a net of air the fish can’t swim through. Chimpanzees have the ability
to work out what others know and are ignorant of18—a skill psychologists
sometimes refer to as “mind-reading.” It was once thought that only humans

had “theory of mind.” And even the human generosity that Wallace described
turns out not to be unique to our species. Life for other animals isn’t con-
stant competition. Many species of animals help to look after each other’s
young and share food.19 Some mammals happily suckle infants that are not
their own.20
And a special evolution
In the years that have passed since the theory of evolution by natural selec-
tion was first proposed, scientists have solved the mystery of genetic inherit-
ance and now understand many of its mechanisms in astonishing detail. But
while some mysteries have been solved, quite a few things that once seemed
straightforward have been revealed to be mysterious. For example, in the 19th
century it seemed obvious how children “inherit” their parent’s language.
They listen to people around them and copy the way they talk. The mystery
was how a child inherited her curly hair from her mother and her shyness
from her father. Today we know how information coded in the DNA directs
the formation of our hair follicles and psychologists are testing theories about
how certain genes influence personality. But the details of how we “inherit”
information by learning is now seen to be much more of a mystery. For ex-
ample, children don’t inherit their parent’s way of talking, but instead tend to
pick up the dialect of their friends. Sometimes when siblings attend different
schools and have different friends, they end up speaking with different ac-
cents. What goes on to make this happen?
Over the last few decades, more and more evolutionists have come to be-
lieve that Alfred Russel Wallace’s idea of a second evolutionary process might
not be so far-fetched. They don’t think that this evolution takes place in a spirit
world. (If a spirit world does exist, it’s not been possible to obtain any reliable
evidence of it, so it’s not amenable to scientific investigation.) But we have
long known that another evolutionary process profoundly impacts human
lives—the evolution of our cultures. We know that culture changes over time.
It changes fast enough that we can experience cultural evolution in our own
lifetimes. Our technology develops, bits of our human-built world are des-
troyed while other things are added, and we’re often aware that our feelings
and beliefs have changed.
In its broadest sense, culture is the monstrously complex, swirling mass
of ideas, beliefs, habits, customs, fashions, and things that surround us. Our
beliefs and emotions seem so personal to us, but they’re connected to what
16 A story of us
people around us do. Our minds change, sometimes without our under-
standing why. We can suddenly start to question something we once took for
granted. It might be something trivial—like whether or not women over 30
should wear leggings—or something more profound—like whether anyone
has the right to voice an opinion about what women over 30 should wear.
Some scholars have argued that “culture” is outside science’s scope—more
of the spirit than the physical brain. Others point out that because science is
part of culture, it’s impossible to have a “science of culture.” They argue that a
person simply can’t take an objective (“scientific”) view of something that he
or she is inside of and part of.21
But a broader definition sees culture as just information— the vast
amount of data that we access via our social networks. Cultural information
is like a set of “tools” that we use to operate in our world. Sometimes our cul-
tural information allows us to create or use physical tools—such as a knife
or the warm clothing necessary to survive in a cold environment. But our
knowledge about our environment—such as what plants are good to eat—is
also an important survival tool. Many of the tools our culture gives us are
“social tools” that allow us to interact with one another in complex ways.
Language is probably the most important social tool—it’s been used by our
ancestors for tens of thousands of generations. But our culture provides us
with many other social tools. We have agreed-upon rules for how to behave
in “polite society,” as well as physical objects, like money, to make it easier to
trade. There are drugs, like alcohol, that can make people feel more relaxed
interacting with strangers, and there are weapons to use when interactions
get hostile.
In the past, separate populations each had their own cultural network.
Some groups lived their lives in complete isolation. But over the last few thou-
sand years, links between populations strengthened, allowing information,
goods, and people to travel more easily between them. Nowadays, there’s a
global network and we’re super-connected. Each of us has access to some
parts of the network and, because people are always editing and adding data,
culture is constantly changing. The change isn’t random, and neither is the
way we access cultural information. Finding and evaluating patterns in the
movement of information is beyond the processing power of our brains. But
the computers we’re building are getting better and better at handling data
and they’re capable of being far more objective about how to handle it.
It’s impossible to make precise and reliable predictions about how people’s
minds will change. Who would have thought that television programs about
cooking would be so popular when people are spending less and less time
cooking their own food? But there are patterns in culture. People who spend
time together tend to think in similar ways and are more likely to agree on
how “things” need to change. People who spend time together are culturally
similar partly because we prefer to be with people who think like us, but also
because spending time with people influences the way our mind changes—as
the life of Jemmy Button clearly shows.
But even this isn’t predictable. The ether that connects human minds and
allows ideas to flow between them often seems to defy analysis. It seems as
though it might as well be happening in a spirit world. Many of us know only
too well that close family members often perceive aspects of the world very
differently. The thing we call “culture” is woven into our minds. It doesn’t just
supply the clothes we use to decorate our bodies; it also provides the mental
organs we use to digest and metabolize our experiences.
This book tells a backstory that explains how our ancestors managed to har-
ness this culture thing—well, to kind of “harness” it. (Our ancestors used cul-
ture, and their culture used them.) The story goes back a long way. Culture
in its broadest sense isn’t unique to humans. Apes and many other kinds of
animals learn from one another, so a group of these animals can also be said
to have “a culture,” albeit a simple one. Among our ancestors, culture became
huge. Their efforts to survive in new habitats millions of years ago led them
to use culture in new ways. As the Earth’s environment became unstable, it
became more and more important for human populations to have a complex
culture that kept them thinking together so they could cope with new chal-
lenges. This allowed some groups to survive, thrive, and eventually prosper.
The story of the evolution of our species and our cultures begins in the next
chapter, which is about our ape ancestors who lived in an African forest seven
million years ago. Even during this prehuman stage, learning and being con-
nected were important. In apes, however, only one connection is strong—the
bond between a mother and her infant. We believe this had changed by about
three million years ago, which is the setting for chapter 3. By this time our
ancestors had evolved into the kind of ape scientists have named “australo-
pithecines.” Chapter 4 describes the lives of our ancestors who lived about
a million and a half years ago. They were human, physically similar to us in
many ways, and their brain was bigger than the brain of any ape, ancient or
modern. But their brain was still considerably smaller than the brain of hu-
mans today. Chapter 5 is about the ancestors who lived 100,000 years ago.
Physically, they were virtually identical to us, with a brain of the same size. But
their culture was far less complex than any seen in humans today. By the time
we get to the humans we feature in chapter 6, who lived 30,000 years ago, cul-
ture had become far more sophisticated in at least some human groups.
18 A story of us
We cram almost all human history into chapter 7. Many stories have been
told about the people who lived during the time between the end of the last ice
age and today. New evidence and our new understanding of human evolution
suggests new ways of looking at these times. For thousands of years, people
with brains like ours walked an Earth full of natural resources, but their popu-
lation and the impact they had on the planet remained small. Then, a few hun-
dred years ago, things started to change very rapidly. Chapter 8 looks at these
changes and how our species reacted to them. Finally, in a short epilogue, we
speculate about the near future.
2
Ape Ancestor (About Seven Million
Years Ago)
Thanks to technology that allows us to analyze the DNA of different living

things, we do know the basic shape of our family tree. There are three basic
kinds of great ape alive on the planet today (four if you want to include hu-
mans). The ones called chimps and bonobos, who are closely related to each
other, are the ones most closely related to us. We know that at some time in
the past—about six or seven million years ago—there were apes living in the
forests of Africa that link us to the rest of the animal kingdom (see Figure 2.1).
Figure 2.1 Most people know that scientists believe humans are descended from
apes—or maybe that we are apes. But what does this mean exactly? If we tried to draw
the ape family tree, it would be almost all question marks. Scientists may be sure that
humans have ancestors that connect us with the ape family, but none of these ancestors
have been identified for certain, and they all became extinct long ago.
20 A story of us
These apes are our ancestors and they’re also the ancestors of the chimpanzees
and bonobos that live in African forests today.
To work out what our relationship to great apes might mean, scientists are
putting together a picture of what this “last common ancestor” (LCA) was like.
Millions of years ago, one of your ancestors was born in a tree in Africa. Its
first breath drew in warm damp air with a mildewy tropical smell. When it
opened its eyes for the first time, it saw light filtered through many layers of
leaves and branches. And it saw its mother’s fur. If you had been born as this
ancestor, you would have been an ape with a brain about a third the size of
your human brain. We can’t know what it would have been like to think and
feel with this sort of brain. But we do have a fair idea of how you would have
behaved and what your ape life would have been like.1
After eight or nine months of being in your mother’s womb, you slid down her birth
canal with rather more ease than a human newborn. When her contractions began,
your mother stopped foraging and tried to make herself as comfortable as possible
on a tree branch as she pushed you out of her womb. As your head started to emerge,
she reached down to hold it and started to gently pull you out of her body.2 Then
she licked and licked you, removing every trace of amniotic fluid from your skin and
hair. Its flavor, mingled with the smell of healthy baby, was delicious to her. When the
placenta came out, she ate it hungrily. If you had been dead or unhealthy, she might
have eaten you too. But you were healthy, and she felt almost overwhelmed with
love for you.
Compared to human babies, baby apes are scrawny little things—about half
the size and much thinner. In spite of your smaller size, however, you’re more de-
veloped, both physically and mentally, than a newborn human (see Figure 2.2).
In many ways, your level of development at birth is closer to that of a one-year-
old human. Within minutes of your birth, you’re capable of giving a mind-piercing
screech, which lets your mother know how healthy you are. She nudges your face
toward her nipples, trying to get you to suckle. Throughout your infancy you will
make many loud shrieks and screams, alerting your mother to any tiny disruption of
your comfort. Your tiny hands and feet tightly grip the fur of her abdomen. You hold
yourself there for a few seconds but feel yourself slipping and start to scream. She
puts a gentle hand on your back.
Eventually you’ll be able to hold onto her front and help yourself to milk from her
teats as she forages in the trees. During the few weeks it takes for you to fully develop
this skill, you and your mother spend quite a bit of time on the ground. She carries
you around, putting you down briefly to rummage for food in the leaf litter and plants.
Ape ancestor 21
Figure 2.2 When this baby chimpanzee was born, it was more developed, both
physically and mentally, than human newborns. A baby ape’s survival depends
on its being able to cling to the fur of its mother’s abdomen and help itself to milk
from her teats. For most of their waking hours, ape mothers need their hands and
arms free to move around and find food.
She’s never far away and snatches you up again at the slightest sign of danger, but you
screech and scream, hating the feeling of not being in her arms. She has to harden
her heart, because she needs to find food to be able to make the milk you need to sur-
vive. She looks for things that have dropped from the trees—fruits, dead flowers, and
baby birds and eggs that have fallen out of nests. There is also the occasional termite
making its way along a tunnel, as well as snails, spiders, lizards, and caterpillars.
22 A story of us
As soon as your mother gave birth to you, you became the center of her uni-
verse. You and she will be inseparable for the next three years at least, and you will
stay very close to her for at least five years after that. You and your mother have a
companion—a young ape that was your mother’s baby until you were born. Now
you have taken his place. He wants to be close to your mother and he is fascinated
by you, but your mother makes him keep his distance. Oxytocin, the hormone3
that triggered the contractions that pushed you from her womb, also works on her
brain, triggering powerful emotions. This hormone is present at the birth of mam-
mals, and in many of them it causes mothers to bond very strongly with their new-
born. The effect of oxytocin on the emotions of human mothers seems to be weaker.
Human mothers can become very absorbed with their new baby, but even the most
ardent human mother proudly hands her infant over to friends, family members,
midwives, and pediatricians. An ape mother is obsessed with her baby. Your ape
mother would have wanted you all to herself and fiercely protected you from eve-
ryone and everything.4
You and your mother spend part of the time with a group of apes. It might be a small
group, comprising only a few adults, but it’s more likely to be larger. During the day,
the group spreads out as its members move around searching for food. Sometimes
the whole group comes together, and sometimes different subgroups form. As
night approaches, each ape finds a suitable place in a tree and quickly weaves some
branches together to make a platform—a sort of nest where it can sleep. You share the
nest that your mother makes.
Finding food in an African forest

Things become easier once you’re able to cling to your mother and hold on tight as
she climbs and swings around the forest canopy looking for food. You’re surrounded
by things to eat. Researchers at the Gombe Stream National Park in Tanzania have
identified 235 different things that are eaten by the chimps that live there,5 and be-
cause the ecology of African rainforest varies from region to region, chimps in other
parts of Africa find different things to eat.
The fact that your mother has survived up to now shows how well she has learned
what there is to eat—and how to get at it. Her problem is that the food is mostly in very
small morsels. Think of being at a buffet restaurant where, instead of the food being
on display, it’s hidden all around the room. When you do find a piece of food, it’s usu-
ally something like a lettuce leaf, celery stick, lemon slice, or one of those little plastic
packets of ketchup—things that might keep you from starving but don’t make you feel
well nourished or satisfied. Some of the hidden morsels are more nourishing. A cock-
tail sausage can usually be found underneath the cucumber slices. A pineapple chunk
sometimes has a cheese cube attached. Your mom is always on the lookout for the
good stuff. She knows that the best morsels are the ones that are hardest to spot and
Ape ancestor 23
get at. Sometimes they’re surrounded by a protective coating that is nasty tasting,
covered in prickles, or impossible to bite through. Your mom is an expert forager. On a
good day, she finds plenty to eat in this cryptic and meager buffet.
Great apes evolved to survive in this habitat. Actually, it’s more correct to say that
apes and their forest homes evolved together. Some of the plants in the forest are
adapted to use apes and other plant-eating animals to spread their seeds. They grow
their seeds inside a fruit that apes find tasty. The apes chew up the fruity package, but
some of the seeds pass through their digestive system unscathed and emerge several
days later, dropping to the forest floor, surrounded by moist feces that will serve as
fertilizer for the seedling that germinates. The symbiotic relationship between apes
and trees works well. Apes eat a lot of fruit. But it isn’t enough to satisfy all their nu-
tritional needs. Plants have evolved to be frugal, and they put just enough nutrition
into their fruit to get apes to eat it. Fruits, leaves, and the other plant bits that apes eat
contain a lot of fiber. Apes can’t digest plant fiber any more than we can. But another
symbiotic relationship helps them get some nourishment from it. Quite a lot of the
fiber can be broken down by the microorganisms that live in the ape’s large intestine.
Apes get extra nourishment by absorbing chemicals that are made and released by
their tiny abdominal tenants. This extra nutrient income is a big help, but it’s still a
struggle for an ape mother to produce enough milk for her growing baby.
The most nutritious foods in the forest aren’t free for the picking. Small animals
or eggs are a lucky find. There are beehives with honey and larvae, but these are sur-
rounded by angry bees. Your mother knows where certain plants store energy. Some
plants put a lot of nourishment in their seeds, some store it in their roots, others
have a carbohydrate-rich pith inside their stems. Over the millennia, the plants and
animals in tropical forests evolved to be better and better at protecting their energy
stores from hungry apes. At the same time, apes became better and better at getting
around these protections. Apes evolved the ability to thoroughly learn the territory
they live in, to remember how it changes throughout the year, and to acquire the skills
necessary to get at the nutritious morsels it contains. But being this clever requires a
large brain, and the larger a brain is, the more energy it needs to function. Even when
animals sleep, their brain is working. So it’s a fine balance—an ape needs a big brain
to find enough food in the meager tropical forest buffet, but the bigger its brain, the
more food it has to find. The balance is most critical for a mother, because she has the
task of finding food for herself and her infant with its brain that needs to grow and
develop.
If your ancestors were like today’s chimpanzees, some of them might have some-
times hunted small monkeys or other similar-sized animals. A chimp monkey-hunt
usually begins when one of the males spies a monkey in a tree and starts to chase it.
Other males join the pursuit, coming at the monkey from all directions, swinging and
jumping through the trees trying to block its escape. If your ape ancestors hunted
24 A story of us
in this way, your mother probably didn’t join in. The chase would have required
a level of speed and agility that’s impossible when carrying a young one. If chim-
panzee hunters manage to catch a monkey, they tear it apart, each hunter trying
get as much as he can. When a hunter has a piece of carcass, he’s surrounded by his
friends begging for a scrap of meat. He keeps the most tender pieces for himself and
allows his special friends to grab the grisly bits. If one of your mother’s friends had
some meat, she would likely be in there begging, but she has her own ways of getting
animal protein. What she lacks in speed and agility she makes up for in ingenuity and
know-how.
Even so, ape mothers can only find so much nutrition in a day. The milk they pro-
duce is very watery and low in nutrition compared to the milk of most other mam-
mals.6 Kittens, for example, get thick creamy milk high in fat and protein, which
supports rapid growth. By about six weeks of age, kittens are weaned and ready
to start learning to hunt. Four months later, the females in the litter will likely be
ready to mate and produce kittens of their own. Female cats can produce several
litters of kittens a year. Apes hardly ever produce more than one baby at a time and
even the best ape mothers seldom manage to raise more than five offspring their
whole life.
The slow growth of baby apes makes it possible for them to survive on low-grade
milk. Once you’re about six months old, you’re of a size that makes it uncomfortable
for your mother to carry you on her front. So she moves you to onto her back. At first
you feel insecure there and you screech and scream. Finally, you get used to bal-
ancing on her back or a nearby branch as she forages. You will gradually grow in size
and strength for another decade or more before reaching your full size and becoming
sexually mature. All primates—the family of mammals that includes apes, monkeys,
lemurs, prosimians, and humans—have a slower metabolism than most mammals,
and they grow and develop more slowly too. Great apes are extreme in this respect.7
And humans are real outliers, strange in a number of ways. More about our strange-
ness in later chapters.
Keeping you alive in a hostile social world

As you grow stronger, your mother must give you a little independence, but this
doesn’t mean she can start to relax. When you’re 18 months old, your brain has
reached its full adult size and you need to play and explore if you’re to learn and
develop. Rough and tumble play is good, especially with your older brother. Your
mother keeps watch and is still fiercely protective. The hormone oxytocin, which was
released during your birth is also released each time you suckle. The physical action
of your sucking on her teats sends a signal to her brain to release oxytocin and so she
continues to feel the powerful emotions that bond her to you.
Ape ancestor 25
Observations of chimps in the wild have shown why natural selection has favored
females who are such obsessively protective mothers. Youngsters are always in
danger. In some groups, researchers have seen an ape tear the infant from the arms
of a groupmate, kill it and eat it with their friends. In times of stress, female chimps
sometimes kill the infant of an unpopular mother—usually a young newcomer to the
group.8 But it’s more often males that kill infants. If you were your ape ancestor, most
of the males in your group would (evolutionarily speaking) have a good reason for
wanting you dead—you would be the offspring of some other male.9 Your mother
probably mated with several of the males when she became pregnant with you; any
of them could be your father and no one knows for sure.
As long as you keep sucking vigorously at her teats no male will have a chance to
mate with your mother. This isn’t just because of the bonding emotions that keep
her focused on you. Your sucking also sends signals to a gland in her brain (the “pi-
tuitary”) causing it to release a hormone called “prolactin.” High prolactin levels in
your mother’s blood have two effects. Prolactin stimulates the mammary glands in
her breasts to keep making milk, and it also prevents the eggs in her ovaries from
ripening. If you die, or even if you just get sick and lose your appetite, the sucking
will stop, and her prolactin levels will fall. Soon after that, one of her eggs will start to
ripen. Once that happens, your mother’s body will no longer be focused on keeping
you alive and will start working to produce a new baby. The ripening egg will trigger
the release of hormones that cause her body to change in ways that make males
want to mate with her. She may also want to mate—but not necessarily. The males
will mate with her without regard to her wants. It has been observed that chim-
panzee males who are the most sexually aggressive toward females, father the most
offspring.10 Primatologists have seen female chimps mating with a male that had
killed her baby a couple of weeks earlier.11
Happily, none of your ape ancestors were victims of infanticide. We know that
they all lived to adulthood and had offspring of their own. Their success was in a
large part due to the mothering they received. This suggests that if you were born
as one of your ape ancestors, your mother would have been older and quite expe-
rienced. The mortality of firstborn apes is much higher than that of their later-born
siblings. First-time mother apes feel a strong bond with their baby, but that isn’t
enough to make them good mothers. It takes great skill to forage efficiently while
caring for an infant. But as with so many of the things that apes do, they get better
with experience. An older mother is also more likely to have formed the friendships
and social ties that help to keep her baby safe in a group where both males and
females might be hostile. An ape group isn’t a herd where animals just live side-by-
side; it’s more like a community, with members who have feelings for one another
and long memories.12
26 A story of us
Their greater competence and better social connections may explain the extraor-
dinary sexual allure of the older female chimpanzee. Primatologists observing chimp
groups report that males virtually ignore the sexual swellings of a young female if she
is ovulating at the same time as an older female who has already raised several off-
spring.13 The males are all busy competing for access to the sagging body and wrinkled
skin of the senior matron. Their preference may seem odd if you’ve been exposed to
glossy magazines and other media promoting the attractiveness of youth. Or if you’ve
read stories of human evolution based on earlier work that placed little emphasis on
the work of females and the importance of parenting. There has been much written
about what “evolutionary theory says” about choosing sexual partners. But what ev-
olutionary theory actually says is that mating is about producing surviving offspring.
If that’s the case, it makes sense that natural selection would favor male apes who are
keen to mate with an experienced mother. In her care, offspring are most likely to thrive.
In the three or four years that you’re dependent on your mother’s milk, you have
plenty of opportunity to see how she lives her life and makes her living. You’re curious
and alert and you learn how she treats the other apes. Having friends is important and
enemies are dangerous. Your mother is careful with the large males, and when she
sees that they have spied a piece of food that she is going after, she drops back and lets
them have it. If she gets it, they will just snatch it from her anyway. She usually forages
on her own with you and your brother and, perhaps, with one of her friends. Friends
make friendly sounds to each other, not talking exactly, but signaling, checking in,
and letting each other know when they’re enjoying food. Friends also spend a lot of
time picking dirt and insects out of each other’s hair. Grooming one another has the
practical value of helping to keep their skin healthy, but apes, like their descendants,
simply enjoy the feeling of touching and being touched. They might sometimes touch
one another in ways that we would consider sexual. While you’re a baby, your mother
is the only one who grooms you. She delicately runs her fingers through your fine fur,
and you learn to love the feel of it.14
Your mother spends most of her waking time foraging and eating. There’s some-
thing about her chewing mouth that fascinates you. You watch her putting things in her
mouth. She’s a very messy eater, so her face and chest are often covered in bits of food.
You pick them off and put them in your mouth, savoring the taste and smell. A colony of
bacteria starts to grow in your large intestine, digesting the plant fiber that you eat. You
suckle whenever you want, but as you grow bigger, the watery milk becomes less sat-
isfying. You watch your mother forage and try to copy her so you can get food for your-
self. Sometimes you’re lucky, but you chew on a lot of nasty-tasting and inedible stuff as
well. Anything that doesn’t kill you makes you wiser. The safest food to eat is stuff your
mother has just found. Sometimes she lets you take a piece of food off her, particularly
if it’s something that needs peeling or pulling apart to get at the edible bit. If she finds
something really nutritious, she’ll ignore your screams and eat it herself. This looks like
Ape ancestor 27
greed and selfishness on her part, but this behavior is essential for your survival. If she
gave you energy-rich food, you would feel less hungry and suck less vigorously on her
teats. If this results in her prolactin levels dropping too low, an egg may start ripening
in one of her ovaries. It’s important for your survival that she doesn’t give birth to her
next baby until you’re able to support yourself with your own foraging. Of course, you
mother knows nothing of pituitaries and prolactin, but for many generations mother
apes who kept all the best food for themselves had more surviving children.
If the growth pattern of your ape ancestor is similar to that of a chimpanzee or bo-
nobo, you’ll be drinking your mother’s watery milk until you’re at least three years
old. Gorilla babies tend to be weaned a little earlier, but orangutan babies are some-
times not weaned until they’re over five years old. As long as you are hungrily suck-
ling, you will be her baby. How fast you learn to forage determines the exact timing of
when her body starts working on her next baby. As you grow bigger, you need to find
more and more food to supplement what you get from her milk. As your foraging skills
improve, your mother starts to push you away when you try to suckle. The tipping
point may come during a season when food is so abundant that even a novice for-
ager is able to find plenty of food. Your suckling diminishes to a point that one of her
eggs begins to ripen. Males in the group begin to get so close to you and your mother
that they make you feel very uncomfortable, but you’re too afraid to make a fuss. She
allows them to get close and she mates with several of them.
Your mother starts to give you more freedom and you soon learn that you must
be careful of certain adults, especially the largest and strongest ones. Everyone takes
care not to make them angry. For eight or nine more months you continue to be your
mother’s closest companion, but then your sibling or half-sibling is born. This scrawny
scrap of screeching life becomes the new center of her universe and you must now
weave your own bed nest at night. You still stay close to your mother because you feel
nervous and because you have quite a bit more to learn about foraging and recog-
nizing the opportunities and risks that surround you. Your mother doesn’t let you get
too close to your baby brother or sister, but unlike the other adults in the group, she
doesn’t mind you following her around as she forages. After several years of this, you
begin to become sexually mature. You never forget your mother, but you’re now ready
to get on with your adult life. You took a long time to grow up, but now you may have
25 or 30 years of life ahead of you.
Why do we think our ape ancestors lived

like this?
We know that our ancestors who lived seven million years ago were apes, so
we can assume that they had ape characteristics. These characteristics would
28 A story of us
have placed certain constraints on how they could live. Two lines of evidence
tell us that, seven million years ago, not only was our ancestor an ape, but it
was an ape that lived in Africa.
First, there is genetic evidence for this. You may have heard it said that
human DNA is 98 percent identical to the DNA of chimpanzees—or 99 per-
cent or 96 percent. The precise number given depends on the technique
used to do the mathematical analysis of the results. All the techniques give a
number close to 100, and this supports Darwin’s conclusion that humans are
descended from African apes. The precise degree of closeness makes it pos-
sible to estimate how long it’s been since an interbreeding population of apes
existed that contained ancestors of both modern humans and modern chim-
panzees. The estimate often given is that this population existed between six
and seven million years ago, but the possibility that a few individuals moved
between populations more recently can’t be ruled out.15
(The same method of genetic reckoning reveals that the common ancestor
of humans and dogs lived about 100 million years ago, and of humans and
insects about 500 million years ago. Two humans living today, even humans
born in very different parts of the world, are likely to have a common ancestor
that lived in the last few thousand years.)
Second, there is fossil evidence (and a lack of it). Very few fossils of human-
like animals have been found that lived earlier than about four million years
ago. This suggests that our early ape ancestors lived in tropical forests. Tropical
forests covered large parts of Africa until about four million years ago, and the
soils of tropical forests tend to be moist, slightly acidic, and teeming with life.
The bones, teeth, and tissues of animals that die in a tropical forest are rapidly
broken down, and the nutrients they contain are recycled into the ecosystem.
A few ancient ape remains have been found, however, perhaps because they
were carried away from the forest by a flooding river or predator and ended up
in a place where they were preserved.
In 1994 over a hundred fragments of bones and teeth from a single indi-
vidual were found in northeastern Ethiopia. Analysis has revealed them to
be from a female ape that lived about 4.4 million years ago (see Figure 2.3).
Bits of bone from similar apes have also been found, and their kind have been
given the name Ardipithecus. The female who possessed this precise skeleton
was given the nickname “Ardi.” Ardipithecus is thought to be at least distantly
related to our ancestors because of the shape of several of the bones in their
skeletons. They’re similar to the shape of the equivalent bones in our skel-
eton, suggesting that these ancient apes were quite comfortable standing and
walking upright on two legs—certainly more comfortable than chimpanzees
and other modern apes. But Ardi probably spent most of her time walking
Ape ancestor 29
Figure 2.3 These are the bones of a female ape that lived about four and a half million
years ago. The shape of some of the bones in her skeleton suggests that, unlike chimps
and other great apes alive today, this ape walked upright, more like we do. But the shape
of the bones in her feet suggest that they are adapted to climbing in trees rather than
walking on the ground. This kind of ape, which has been given the name Ardipithecus,
may have walked upright along tree branches, leaping from branch to branch.
Credit: http://www.sciencemag.org/cgi/content/full/326/5949/64/F3, Fair use, https://en.wikipedia.
org/w/index.php?curid=28198561.
along tree branches rather than the ground. Her foot bones show that her feet
had grasping thumb-like big toes like the big toes of today’s apes. Such toes
are useful for holding onto tree branches but not so good for walking on the
ground. Fragments of foot bones from upright walking apes with forward-
pointing big toes like ours have been found, but they lived more recently. So
the evidence from fossils discovered so far suggests that our ancestors spent
a great deal of their time in trees until about four or five million years ago.16
Primatologists have spent many years making meticulous observations of
the great apes living today—the chimpanzees, bonobos, and gorillas living in
Africa and the orangutans living in the forests of Indonesia. They believe that
their study of these apes provides clues to the lives of our forest-dwelling ape
30 A story of us
ancestors. They’ve been able to work out how ape behavior is shaped by having
an ape body and living with others of their kind in a diverse and complex trop-
ical habitat. The chimpanzee is the most numerous modern ape, and it’s the
one that has been studied most, both in the wild and in captivity. In terms of
their DNA sequences, today’s chimpanzees (and their rarer relatives the bo-
nobos) are as different from our ape ancestors as we are. And they’re even more
different from gorillas and orangutans. But in terms of their bodies and their
lives, today’s chimpanzees are probably not that different from our ancestors.
They were also apes trying to make a living in and around tropical trees.17
We humans are very different and can make a living and create a home in al-
most every habitat on Earth. But information gained by studying today’s apes
allows us to tell the first part of our evolutionary story. It reveals the changes
that have occurred over the last seven million years and shows us what charac-
teristics didn’t change because they were already present in our ape ancestors.
Living with a great ape body and social life
Some aspects of the life of your ape ancestors can be described with confi-
dence.18 They had a great ape body, and we know that this would have pro-
vided them with certain abilities. For example, great apes, like humans, have a
throat and mouth that can be used as an instrument for making a wide range
of noises. Apes aren’t able to make the same speech sounds as humans do, and
the noises they make aren’t “words.” Young apes don’t learn that certain noises
have a symbolic meaning that can be used to communicate complicated in-
formation. Even so, the sounds they make are an important part of ape so-
cial interactions. Their vocalizations are a “social tool.” The screeches, pants,
and grunts communicate feelings rather than ideas, but they’re still useful.
When an angry adult male chimp screams in frustration, smaller group mem-
bers know to keep out of his way, and this reduces the chances of someone
getting hurt.
Having a great ape body also places important constraints on how they can
live their lives. Perhaps most important is their pattern of growth and devel-
opment. There is a little flexibility; in both apes and in humans, for example,
the speed of a youngster’s growth and the age it becomes sexually mature can
vary a bit, depending on how well it’s nourished and perhaps also how well its
mother was nourished.19 But the basic pattern of growth and development
is programmed by its genes. Compared to most mammals, apes grow very
slowly. So do humans, and there can be little doubt that our ape ancestor that
lived millions of years ago was also a slow grower. Because their young grow
Ape ancestor 31
so slowly and have so much to learn, the lives of female apes are much more
constrained than the lives of male apes. For most of their adult lives, female
apes are caring for an infant and may have one or two older offspring hanging
around as well.
The four different great ape species living today organize their social lives
in different ways. Orangutans live on their own, although a mother and her
youngsters live together. Gorillas live in small groups, usually made up of a
male and a couple of females and their young. The apes most closely related
to us, chimps and bonobos, live in much larger groups, often consisting of a
few dozen adults of both sexes and their young. Mother chimps and bonobos
spend a large part of each day foraging on their own with their youngsters, but
the group generally meets up as evening approaches and the members tend to
sleep in a group of adjacent trees.
Since we humans also organize ourselves into large social groups, it seems
a fair guess that the ancestors that we share with chimps and bonobos lived
in social groups similar to theirs. If so, these groups were probably organ-
ized into a hierarchy, with higher-ranked group members dominating the
lower orders and getting their own way. The hierarchical behaviors seen in
chimpanzee and bonobo groups look very antisocial to our eyes, but conflict
is bound to occur in a community of individuals who are competing to find
food in the same limited territory. Hierarchical behavior isn’t cooperative,
but it does tend to reduce the fierceness of the competition. Everyone is safer
when it’s routine for those lower down the ranks to simply give in. That way,
fighting only happens when lower-ranked members think they have a real-
istic chance of moving up and replacing someone above them. Hierarchy,
therefore, is a second “social tool” that our ape ancestors probably used to
make their lives easier. Once hierarchies are established, members of the
lower orders might decide to cooperate. For example, among both chimps
and bonobos, males are larger and will be aggressive to get what they want.
In bonobo groups the females often form alliances and support each other.
Bonobo males are still aggressive toward females, but they don’t dominate
them to the extent seen in chimp groups.
Grooming is a third “social tool” that apes employ to improve their lives,
and it’s also used by many other group-living mammals. Mammals stay
healthier if their skin and fur are regularly groomed to remove dirt and in-
sect parasites like ticks and fleas. But grooming often has an important so-
cial and psychological function as well.20 Many group-living mammals form
friendships, and special friends tend to groom one another (see Figure 2.4).
They spend quite a bit of their day licking, biting, scratching, or picking away
at each other’s skin and hair. It’s stressful to be always looking for food and
32 A story of us
Figure 2.4 As apes carefully remove bits of dirt, dead skin, and insects from the skin of
their friends, they demonstrate their trust and their trustworthiness.
Picture credit: Thomas Deco.
keeping out of the way of the dominant male, especially when you also have
a baby to protect. It must help to have some groupmates that you really trust.
By allowing themselves to be touched, often in intimate sensitive places,
grooming partners show one another that they feel trust. If a grooming ses-
sion goes well, it helps cement their friendship. The partners are reminded
that their trust is well placed. But there’s more going on that just learning.
The bodies of social mammals release chemicals during grooming that in-
fluence their mood. Being groomed feels good. Oxytocin, the hormone that
causes mothers to bond with their babies, is released during a nice grooming
session, so the bonds of friendship that animals create and maintain when
they carefully touch one another is supported by the same hormone system
that supports the fierce mother-infant bond.
Different kinds of animals have different ways of grooming, which isn’t sur-
prising, because they have quite different bodies. But there are differences, even
among apes. For example, bonobo grooming involves much more touching
of sexual organs than among either chimps or gorillas. What’s more, some of
the most active touching of sexual organs occurs between bonobos who don’t
know one another very well. A friend of ours who observes bonobos in the wild
told us that this grooming seems more like a social obligation with grumpy
Ape ancestor 33
neighbors than a pleasant, relaxed time with friends.21 Some grooming may be
more about keeping the peace than skin care and friendship.
It could be said that the ape body is programmed by their genes to enjoy
being groomed, but this doesn’t mean that grooming behavior is programmed
into apes. Exactly how ape friends touch one another varies between friend-
ships and between groups as well as between species. If grooming is a social
tool that some mammals use to help them form and keep friendships, then the
cleverness of apes allows them to develop this tool and add individual touches.
Genes indirectly influence ape behavior by providing them with an ape body.
The structure and functioning of its body define what an animal can do and
feel, and what its limits are. But, like us, apes gather information throughout
their lives, and this learning influences how they behave. Short-lived animals
with small brains are known to respond to certain situations in set ways,22 but
apes are long-lived and have large brains.23
Apes are also able to get around some of the constraints placed on them by
their body. For example, a female chimp can’t help advertising to the males
around her that she is becoming fertile, and the males can’t help wanting to
mate with her. When an egg is ripening in one of her ovaries, a female chimp
can’t prevent the tissues around her vaginal opening absorbing water so that
they swell up and start to protrude several centimeters behind her crotch. As
the egg becomes ripe, the skin of the swollen area absorbs extra blood, be-
coming warm and red. Male chimps find this extremely attractive and, be-
cause males are much stronger, females don’t really have a choice about
mating. During her fertile period a female chimp may mate 30 or more times
and with several different males. But this doesn’t always happen. Several pri-
matologists have reported observing a female disappearing with a single male
for several days. She seems to spend her whole fertile period with him. (We
say “seems” because it’s impossible to know for sure. Primatologists following
chimps around their habitat can only see what they manage to see, and it’s pos-
sible that other males did see and mount the fertile female when the human
voyeurs had lost track of her.) But what these observations show is that female
chimps don’t seem to be “programmed” to have sex with many males. We can’t
conclude that our female ape ancestors were either.24
We also can’t know if our female ape ancestors who lived seven million
years ago had sexual swellings or gave any other sign that they were ovu-
lating. Chimps and bonobos signal their fertility with sexual swellings, but
these aren’t a general ape characteristic. Neither gorillas nor orangutan fe-
males advertise their ovulation in such an obvious way, and, of course, nei-
ther do human females. Nor can we know about the structure of the groups
that our ape ancestors lived in. Primatologists describe chimps and bonobos
34 A story of us
as “male philopatric,” which means that males generally spend their whole
lives in their mother’s group (which is also usually their father’s group).
Their sisters tend to move to a different group. We can’t conclude from this
that male chimps are genetically programmed to stay near their mother
and females are programmed to want to leave her. It may just be the most
reasonable thing to do. A female is usually accepted if she moves to a new
group, while a male venturing into the territory of another group is likely
to be killed by males from that group. Some female chimps do choose to
stay near their mother, but they pay a price. Many of the males in the group
are their close relatives. A baby conceived through mating with her father
or brother is less likely to be healthy than a less inbred baby. A female has
the best chance of reproducing successfully if she goes to another group’s
territory and tries to fit in with them. That’s what most female chimps and
bonobos do. It’s interesting to try to imagine the feelings and perceptions of
a young female chimp as she decides to leave her mother and venture into
an unknown community. But we can’t know what it’s like to experience life
with a brain so different from our own.25
Given what we said earlier in this chapter about mothers being obsessively
bonded to their offspring and entirely responsible for their care, it’s important
to point out that there is also some flexibility here. Some mother chimps have
been observed to allow certain trusted individuals to hold their baby, such as
their own mother, an older offspring, or even a human primatologist. And,
although males don’t usually care for infants and youngsters, males have been
observed walking around with an orphaned infant clutching onto their ab-
domen. Males have even been spotted giving food to a hungry orphan. If a
mother chimp dies before her infant is weaned, its chances of survival are slim.
But orphaned juveniles aged five or six who still need to follow their mother
around are sometimes “adopted” by another more experienced female, and
sometimes by a male. The adopter is most likely to be an older sibling or a
friend of their mother.26
Culture introduces more flexibility
The behavior of the apes and humans living today is strongly influenced by
the cultural legacy they receive, and this was almost certainly also true for our
common ancestor with chimpanzees and bonobos that lived seven million
years ago. 27 When people think about what nonhuman animals inherit from
their parents, they tend to think only about genes. We humans might inherit
houses, old-fashioned furniture and some photographs from our parents, but
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A Story of Us A New Look at Human Evolution Lesley Newson Full Chapter PDF

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A Story of Us: A New Look at Human

Evolution Lesley Newson

The Spaces Between Us: A Story of Neuroscience,

A Better Ape: The Evolution of the Moral Mind and How

A First Look at Communication Theory 10th Edition,

A First Look at Communication Theory - 11th Edition Em

Preacher Woman: A Critical Look at Sexism without

The PlayBook: An Inside Look at How to Think Like a

A First Look at Communication Theory, 11th Edition

The Paramedic at Work: A Sociology of a New Profession

Lesley Newson and Peter J. Richerson

DOI: 10.1093/ oso/ 9780190883201.001.0001

1. Getting Beyond the Apemen 1

2. Ape Ancestor (About Seven Million Years Ago) 19

3. Apes That Walked Upright (About Three Million Years Ago) 38

4. Early Humans (About 1.5 Million Years Ago) 59

5. Humans Like Us (About 100,000 Years Ago) 79

6. Ice Age Humans (30,000 Years Ago) 113

7. Building Today’s World 144

8. Another Transformation: Modern Times 188

needed. In a matter of days, people found their lives dramatically changed

New ways of thinking about thinking

When humans puzzle over something abstract like “what is thinking?,” we

Figure 1.1 The path from the forest.

hardware upgrades, imagining improvements in things like processing speed

Stories are tools for thinking, and so

evolution is amazing and unique. We humans have a history we can be proud

The special species

Nowadays, many people believe there’s nothing special about humans—​

sometimes refer to as “mind-​reading.” It was once thought that only humans

And a special evolution

Thanks to technology that allows us to analyze the DNA of different living

Finding food in an African forest

Keeping you alive in a hostile social world

Why do we think our ape ancestors lived

Living with a great ape body and social life

Culture introduces more flexibility

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The Foundation is committed to complying with the laws

1. Getting Beyond the Apemen 1

2. Ape Ancestor (About Seven Million Years Ago) 19

3. Apes That Walked Upright (About Three Million Years Ago) 38

4. Early Humans (About 1.5 Million Years Ago) 59

5. Humans Like Us (About 100,000 Years Ago) 79

6. Ice Age Humans (30,000 Years Ago) 113

7. Building Today’s World 144

8. Another Transformation: Modern Times 188

Nowadays, many people believe there’s nothing special about humans—

sometimes refer to as “mind-reading.” It was once thought that only humans